Sunday, October 11, 2015

I've recently been battling the effects of too little sleep and too much work for too long, so my posts have been spottier than usual lately. I'm starting to make inroads on the exhaustion, though, so I thought I'd give you another Daily Apple. This one is about a little inconsistency I noticed this afternoon.

October is the tenth month in our calendar. But clearly, octo- means eight. How did a month named "eighth month" wind up in the tenth spot?

And wait a minute. September = 7, November =9, December = 10. But they are in the 9th, 11th, and 12th month positions. How did that happen?

The Short Answer

As you might guess, it's because of the transition from an old calendar to the calendar which we now use.

In the very old Roman calendar, October was the 8th month. When the Roman calendar was revised, more months were added, and that pushed October into the 10th slot.

The Complete Answer

Regular Daily Apple readers will know that a three-sentence answer to any question is probably not the entire answer. The complete answer may take longer to get to, but therein lie the oddities, and therein lies the fun.

First of all, the Romans didn't quite have it all down pat when it came to their calendar. They got their ideas about their calendar from the Greeks, but they added their own special flair to it.

Initially (before 700 BCE or so), their calendar had 10 months. Nice, round number. Easy to work with. The months were ordered thusly:

Martius

Aprilis

Maius

Junius

Qunitilis

Sextilis

September

October

November

December

You can see the Romans trying to be logical. They were creative with the first 4 months' names, and then they gave up and named the months after their position. But that made things easy to keep track of.

The problem was, the earth's rotations and the months and days don't fit nicely into a 10-month package. The Romans wound up with 61 days that didn't belong to any month at all.

I don't know what people did for those 61 days. Went around holding their breath, I suppose, or saying, "We are in the monthless days," I don't know.

Then Numa Pompilius, the second king of Rome--this was before there were emperors or even a republic--came along. He ruled from 615-673 BCE, after the first king, Romulus, had died. He decided to reform the calendar and account for those rogue 61 days.

Sculpture of Numa Pompilius. I'm talking about him as if he were an actual person, and he was, but he lived so long ago, and so many stories have been told and re-written and exaggerated that it's difficult to know what he actually did and what was done by other people and got attributed to him. From what I gather, he's sort of a catch-all figure for Things People Did During the 700 BCE years.(Image from Crystalinks)

Numa added two more months, January and February, at the end of the calendar. So his months went like this:

Martius

Aprilis

Maius

Junius

Qunitilis

Sextilis

September

October

November

December

January

February

He preserved the logic of the months' names and their positions, and his calendar came closer to the actual solar year, but it fell a little short at 355 days long.

To correct that problem, he said that every other year there should be an inter-calendar month of 22 or 23 days, whichever was necessary, called Mercedinus.

You would think that Mercedinus would be inserted after February, but that's not quite how it went. Numa said Mercedinus should be inserted within February, after the 23rd or 24th, and then once Mercedinus was over, they'd go back to February and finish that month. So in practice his calendar went more like this:

1. Martius

2. Aprilis

3. Maius

4. Junius

5. Qunitilis

6. Sextilis

7. September

8. October

9. November

10. December

11. Januarius

12. Februarius

(no number). Mercedinus for a while

12. back to Februarius

Numa also declared that the previous practice of figuring out what day it was solely by what the moon was doing was too fuzzy. From then on, every month would have 31 days. Er, mostly.

The Romans liked 31 because they believed that odd numbers were lucky. But not every month could have 31 days and keep the calendar corresponding with actuality, so Numa said some months would have 29 days. Keepin' it odd.

But even with these improvements, the Roman calendar was still messed up. The months wound up moving slightly as time progressed so a month that used to be in spring, after a certain amount of time, would wind up in summer.

Also, since the priests were still in charge of announcing when it would be the Ides or when it would be the Kalends, they were messing with the decrees to make parts of a month longer or shorter so the rulers they liked would be in power longer. There were decrees being made left and right, changing the length of months all the time. The whole thing got pretty jacked.

Replica of a fragment of a Roman calendar (one of the Fasti), showing January through May. Days were reckoned by the new moon (Kalends) and how many days had passed since that, the first quarter (Nones) and how many days after that, and the full moon (Ides) and how many days had passed since then. Crystal clear, right?(Figure from Calendars through the Ages)

When Julius Caesar came along, he said, "I'll fix this." He asked an astronomer for advice and based on what that guy told him, in 45 B.C.E. he established a new calendar that had 365 days (10 more than the Roman calendar) divided into 12 months. Sounds familiar, doesn't it?

Julius Caesar, perhaps decreeing that we should all abide by his new and improved calendar.(Photo from Calendars through the Ages)

He made January the first month of the year. This was in keeping with a practice that many people had been following for about 100 years already because January 1 was the beginning of the civil year in Rome, when the elected consuls would begin their one-year term. (Sort of ironic that Caesar, who inaugurated the empire and put an end to the Republic, would codify a practice associated with the rule of the republicans).

He didn't change the order of any of the months, just shifted the beginning of the year to January. So his calendar went like this:

But Wait, There's More

After a few years, the astronomers discovered the Julian calendar wasn't right. So they added a Leap Day at the end of February every third year. But then after a few more years it became obvious that still wasn't right, so they changed Leap Day to every fourth year.

After more time passed, they discovered that this still wasn't right. An extra day was getting added every 128 years. So every 128 years, they had to shift the calendar to skip that extra day.

Even so, that calendar was pretty popular and some parts of the world or some scholarly disciplines still use it.

In 1582 during the tenure of Pope Gregory XIII, a new calendar was adopted, which we call the Gregorian calendar after the Pope, even though it was an Italian astronomer who came up with it.

Luigi Lilio, the Italian doctor/philosopher/astronomer who came up with the calendar we call Gregorian and which we use today.(Image from adnkronos)

The Gregorian calendar was pretty much the same as the Julian calendar, except the number of days in each month were a little more flexible -- no need to stick with that lucky odd number anymore -- and the months were adjusted so the first day of a new season fell on the 21st, or as close to that as possible, and the way Leap Day was calculated was more nuanced.

Leap Years would not be every fourth year absolutely, but would occur only if the year is evenly divisible by 4. But if the year is evenly divisible by 100 it is not a leap year, unless the year is also evenly divisible by 400.

This got rid of that problem of an extra day every 128 years, and it also helped keep the months more closely aligned with the seasons each year. It is the calendar we follow today.

By the way, English-speaking folk took longer to switch to the Gregorian calendar. It wasn't until 1752 that Great Britain and the then-colonies began counting their days the Gregorian way.

The Gregorian calendar still isn't perfect, by the way. It adds an extra 27 seconds each year, which amounts to 1 extra day every 3,236 years. In a few thousand years, somebody will have to tweak our calendar some more.

Another indicator of how the Gregorian calendar still contains errors. You can see how the calendar date of the summer solstice falls at various times relative to June 21.5 as the years progress, and then gets readjusted with the divisible-by-400 leap shifting. If our calendar has this much variation in it, imagine how much variation there must have been in the Roman calendar compared to seasons and equinoxes.(Chart from Wikipedia)

Bonus Fact

In the very early days of the Roman kings, a priest (pontifex) would keep track of what the moon was doing and when a new moon started, the pontifex would announce that a new month had begun. The verb for "to solemnly announce" is calare, and it is from that verb that we get our word calendar.

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